During the research of American scientists found that people choose their friends based on similarity of the vote. Usually this factor is not taken into account, as it is formed unconsciously.
To prove their theory, the researchers conducted a study involving men and women. Scientists studied the circle of friends of the subjects. Experts believe that there are special acoustic signals, determining a characteristic of the voice. They serve as the identification sign for a tighter communication when meeting.
The result is two people with similar voices converge faster and become friends. Partial or conditional coincidence signals.
Note that previously, scientists have conducted research that proves the link between human voice and its growth.